The "Update in Perioperative Medicine" provided a review of relevant studies of clinical relevance by presenters Steven L. Cohn, MD, FACP, chief of the Division of General Internal Medicine at SUNY Downstate, Brooklyn, N.Y.; Gerald W. Smetana, MD, FACP, associate professor of medicine at Beth Israel Deaconess Medical Center, Harvard Medical School, Boston; and Amir K. Jaffer, MD, a medical director at the Cleveland Clinic Foundation, Ohio.
Dr. Smetana began with a summary of three articles published in 2006 that provide a review of literature on preoperative pulmonary evaluation and serve as a guideline for clinicians for the perioperative period.1-3 The 325 eligible studies in the review found the following conclusions: A limited number of patient- and procedure-related risk factors accurately predict risk, routine spirometry and chest radiography add no benefit, and postoperative lung expansion maneuvers are the most effective risk reduction strategy.
A separate study showed that two weeks of preoperative intensive, inspiratory muscle training reduced pulmonary complications and length of stay after elective coronary bypass surgery.4 "This adds to the body of information that suggests the value of lung expansion maneuvers," said Dr. Smetana.
A recent retrospective chart review compared the complications of noncardiac surgery among patients undergoing preoperative coronary angioplasty versus coronary stenting.5 Researchers found high rates of bleeding, myocardial infarction (MI), and death for noncardiac surgery patients within three months of percutaneous coronary intervention (PCI). Risks were comparable for patients undergoing plain angioplasty or coronary artery stenting. "These findings suggest that we should not perform PCI on patients planning elective surgery within three months," warned Dr. Smetana.
Dr. Jaffer began with a summary of the American College of Cardiology/American Heart Association Advisory, "Antiplatelet Therapy and Noncardiac Surgery," which states that "A bare-metal stent [BMS] or balloon angioplasty should be considered if patients need surgery within 12 months," and "Elective procedures should be delayed until a month after BMS or 12 months post DES [drug-eluding stent] implantation."
A prospective outcome study of coronary artery stenting and noncardiac surgery found that the incidence of major cardiovascular events after noncardiac surgery was high for up to one year after PCI.6 A standardized perioperative heparin and antiplatelet protocol does not reduce this risk.
"This paper has a pretty significant impact," said Dr. Jaffer.
Dr. Cohn then covered pharmacologic strategies for reducing postoperative cardiac complications. A 2006 study examined the effects of metoprolol on cardiac complications 30 days and six months after vascular surgery. 7 The control group of 250 patients had a 12% complication rate at 30 days, compared with a 10.2% complication rate of the 246 patients on metoprolol. At six months, the event rate also showed no significant difference, but adverse effects requiring treatment were more frequent in the metoprolol group.
"The absence of benefit and frequent adverse effects question the recommendations for prophylactic beta-blockers," said Dr. Cohn.
A Dutch study looked at whether a higher dose of beta-blockers and tight heart rate control were associated with reduced perioperative myocardial ischemia, troponin T release, and improved long-term outcome.8 Among 272 vascular surgery patients, higher beta-blocker doses were associated with a lower incidence of myocardial ischemia, troponin T release, and long-term mortality. Higher heart rates were associated with an increased incidence of these factors.
"This study indicates that hospitals should develop protocols using dose titration to ensure adequate beta-blockade and heart rate control," said Dr. Cohn. "How to do this is a major problem, but it is recommended."
A separate Dutch study assessed the value of preoperative cardiac testing in intermediate risk patients receiving perioperative beta-blockers with tight heart rate control scheduled for vascular surgery.9 Researchers found that 30-day and long-term cardiac death and MI rate in these patients was sufficiently low to preclude preoperative testing for coronary disease-provided that beta-blockers are prescribed for tight heart rate control.
"This will significantly alter the current approach," Dr. Cohn pointed out, "as well as the ACC algorithm for preoperative diagnostic testing."
Dr. Cohn ended by covering a review of the perioperative beta-blocker literature published in 2006, which aimed to update recommendations for national quality initiatives before the new guidelines are released.10 However, the recommendations based on this review were not deemed to be definitive enough, noted Dr. Cohn.
Dr. Jaffer outlined recent research on preoperative anticoagulant activity of low-molecular-weight heparin (LMWH) following a standardized bridging regimen.11 Researchers found that anti-Xa levels remain high at the time of surgery if the last dose of twice-daily LMWH is given the evening before. "The last dose of LMWH should be given in the morning of the day before surgery," said Dr. Jaffer. However, he pointed out that the study was too small to provide an accurate estimate of the clinical outcomes.
Dr. Jaffer went on to summarize two recent papers on venous thromboembolism (VTE), beginning with a study that evaluated the efficacy and safety of a four-week treatment of 5,000 IUs of dalteparin once a day, compared with one week of this dose, following major abdominal surgery.12
The researchers found that late VTE occurred in one out of every six patients following surgery, despite a one-week course of thromboprophylaxis. "You would need to prolong prophylaxis for 12 patients to prevent one VTE," Dr. Jaffer said. This was the first study to show that administration of dalteparin 5000 IUs daily for four weeks reduces the rate of VTE without compromising safety in abdominal surgery patients.
A second study set out to better characterize the incidence and risk factors for pulmonary embolism (PE) after bariatric surgery over a 24-year period at one tertiary care center.13 Their data show that one-third of PE occurred after discharge, and a role was seen for extended prophylaxis. "But we need better data," said Dr. Jaffer. Perhaps even more aggressive prophylaxis should be used with patients with high body mass index, obesity hypoventilation syndrome, and venous insufficiency.
The last paper covered was "Principles of Effective Consultation: An Update for the 21st Century Consultant."14
"This holds a lot of implications for our practice," said Dr. Jaffer. The paper compared expectations of consultants from different specialties and examined the findings.